1. Field of the Invention
The present invention relates to an automobile reducer and, more particularly, to an automobile reducer capable of compensating for an excessively large or excessively small clearance, which is caused by an error related to manufacturing or assembling of a housing and a worm shaft bearing, and an excessively large backlash in connection with a worm shaft, which is caused by wear of a worm wheel, the automobile reducer being capable of compensating for an excessively small backlash in connection with the worm shaft, which is caused by moisture-absorbing expansion of the worm wheel, and the automobile reducer being capable of buffering the resisting force of the worm shaft with regard to the worm wheel, which results from an abrupt rotation of the worm wheel or from a change in the direction of rotation, thereby accurately assisting the driver's manipulation of the steering wheel.
2. Description of the Prior Art
FIG. 1 is a sectional view illustrating a conventional automobile reducer. As illustrated in FIG. 1, the conventional automobile reducer 100 is provided with a worm shaft 154, which has a worm 152 formed thereon. Worm shaft bearings 157 are formed on both ends of the worm shaft 154, respectively, so as to support the worm shaft 154. In order to prevent the worm shaft bearings 157 from playing in the axial direction of the worm shaft 154, a plug bolt 110 is fastened between a damping coupler 140 and the worm shaft bearings 157, and the plug bolt 110 is fixed by a plug nut 120.
The worm shaft 154 is connected to a motor 146 via the damping coupler 140, and the worm shaft 154 is structured to be rotated by driving of the motor 146.
In addition, a worm wheel 156 is provided on the outer diameter of the worm 152 so as to be able to mesh with the worm 152, which is formed on the worm shaft 154. The worm shaft 156 is mounted on a steering shaft 106, which transmits a rotating force of a steering wheel (not illustrated) manipulated by the driver, thereby providing such a structure that the rotating force of the worm shaft 154, which results from driving of the motor 146, is transferred to the steering shaft 106.
A gear housing 160 contains the worm 152, the worm wheel 156, and the like. The motor 146 is provided on one side of the gear housing 160 so as to provide the worm shaft 154 with a driving force. The gear housing 160 and the motor 146 are coupled through a bolt 150 by means of a motor cover 130.
An automobile reducer, which has a structure as described above, operates as follows: driving of the motor is controlled by an electronic control device, which is provided on the vehicle, according to the vehicle traveling condition, and the rotating force of the worm shaft, which results from driving of the motor, is added to the rotating force of the steering wheel, which is manipulated by the driver, and then transferred to the steering wheel, thereby maintaining the driver's steering driving state smoothly and stably.
However, there is a problem in that, if a resisting force occurs with regard to the worm wheel of the worm shaft due to an abrupt rotation of the worm wheel or a change in the direction of rotation, which results from an excessively large or excessively small clearance in connection with the housing caused by an error related to manufacturing or assembling of the housing and the worm shaft bearings, the worm shaft bearings come to collide inside the housing and generate rattle noise, thereby inconveniencing the driver.
There is another problem in that an excessively large or excessively small backlash in connection with the worm shaft occurs due to wear of the worm wheel or moisture-absorbing expansion of the worm wheel; such a backlash makes it impossible to accurately transfer a steering assist force, which assists the driver's steering wheel manipulating force, and generates loss of power between the worm shaft and the worm wheel; and the driver fails to be provided with the accurate steering assist force, meaning that the driver's steering feeling is degraded.